UNIVERSIDAD METROPOLITANA SCHOOL OF ENVIRONMENTAL AFFAIRS ...€¦ · UNIVERSIDAD METROPOLITANA. SCHOOL OF ENVIRONMENTAL AFFAIRS. SAN JUAN, ... Foundation and its coordinator Lisa

UNIVERSIDAD METROPOLITANA

SCHOOL OF ENVIRONMENTAL AFFAIRS

SAN JUAN, PUERTO RICO

INTERACTION BETWEEN THE DUNE APHID SCHIZAPHIS RUFULA AND

ITS HOST-PLANT AMMOPHILA ARENARIA: A COMPARISON OF INSECT

MULTIPLICATION ON DIFFERENT HOST-PLANT POPULATIONS

Partial requisite for the acquirement of the

Degree of Master’s in Science in Environmental Management

Specialization in Natural Resource Management and Conservation

By

Jeselyn Calderón-Ayala

December, 4, 2012

DEDICATION

To mom, dad, my 3 sisters and Leinã’ala

For their never ending support and for being pillars, not only in my life, but for my

career endeavors

Thank you; receive all my gratitude, and all my love.

ACKNOWLEDGEMENTS

First of all, I want to give thanks to Dr. Eduardo de la Peña, for inviting me to work in his

laboratory and trusting me with this amazing opportunity that has change my career, forever.

Without him this work would not have been possible, and my love for the coastal ecosystems

would have stayed submissive. To Dries Bonte and Luc Lens for letting me work in the

Terrestrial Ecology Unit (TEREC) without any doubt or hesitation. To Martijn L. Vandegehuchte

for providing indirect guidance with his previous work on Ammophila arenaria systems.

To the School of Environmental Affairs, for their permission to let me choose my own

research line and be able to work it abroad, at a continental scale. To the Office of Internships

and Scholarships of Universidad Metropolitana, especially to its Vice-rector Jacqueline E.

Guzmán-Silva and the Annual Fund, for always believing in me. To the José Jaime Pierluisi

Foundation and its coordinator Lisa Ramirez and to the Puerto Rico Council on Higher Education

(CES-PRIDCO) for providing extra funding in order for me to achieve my desire to do research

and have a learning experience overseas. To Leinã’ala S. Hall from University of Hawai’i at

Hilo and the ESA/SEEDS Network, not for only helping me in-situ with the research work in

Belgium, but for proofreading and editing the document in whole. I am tremendously grateful to

have worked with a student with such quality; without Leinã’ala this Thesis would not have been

translated into English.

Last but not least I want to thank Dr. Juan F. Arratia for exposing me to the initial

opportunity that eventually led to the collaboration between my Advisor, Dr. Eduardo de la Peña,

and myself. In addition, I want to thank Dr. Arratia for providing the funds to meet my Advisor in

Portland, Oregon to summarize the results of this research and also, to be able to present it at the

2012 Ecological Society of America (ESA) Annual Meeting.

v

TABLE OF CONTENT

List of tables ..................................................................................................................... vi

List of figures .................................................................................................................. vii

List of appendices .......................................................................................................... viii

Resumen ........................................................................................................................... ix

Abstract. ............................................................................................................................ x

CHAPTER I: INTRODUCTION .................................................................................. 1

Background of the problem ..................................................................................... 1

Statement of the Problem ........................................................................................ 5

Justification.............................................................................................................. 6

Research question .................................................................................................... 7

Goal ......................................................................................................................... 7

Objective.................................................................................................................. 7

CHAPTER II: LITERATURE REVIEW ..................................................................... 8

Historical background ............................................................................................. 8

Conceptual/theoretical framework ........................................................................ 10

Case studies ........................................................................................................... 16

Legal frame ............................................................................................................ 18

CHAPTER III: METHODOLOGY ............................................................................ 24

Seeds handling ....................................................................................................... 24

Aphid handling ...................................................................................................... 26

Data analysis .......................................................................................................... 27

CHAPTER IV: RESULTS AND DISCUSSION ......................................................... 28

CHAPTER V: CONCLUSIONS AND RECOMMENDATIONS ............................. 31

LITERATURE CITED ................................................................................................. 36

vi

LIST OF TABLES

Table 1. Results for daily populations of aphids on individual plants ........................... 42

vii

LIST OF FIGURES

Figure 1. Aphids vs. time population growth curve ....................................................... 46

Figure 2. Geographical areas demonstrating seed pool collection points ...................... 47

Figure 3. Geographical areas demonstrating seed pool collection points, Belgium ...... 48

Figure 4. Geographical areas demonstrating seed pool collection points, U. K. .......... 49

Figure 5. Geographical areas demonstrating seed pool collection points, Portugal ...... 50

viii

LIST OF APPENDICES

Appendix 1. Example of data collection sheet ………………………………………….52

Appendix 2. Ghent University acceptance letter ……………………………………….53

Appendix 3. Ammophila arenaria host-plants and aphids ……………………………...54

Appendix 4. Experimental seedlings planted on the pots ………………………………55

Appendix 5. Ammophila arenaria grass in-situ, Belgium ……………………………...56

Appendix 6. Central mobile dune system, Belgium ……………………………………57

Appendix 7. Dune ecosystem access restriction, Belgium ……………………………..58

ix

RESUMEN

Las dunas costeras son grandes acumulaciones de arena que se encuentran a lo largo de la

costa, formadas por corrientes marinas, oleaje, viento y vegetación. La vegetación

provee la estabilización de la duna, creando a su vez un hábitat idóneo para un sin

número de organismos como insectos, crustáceos, reptiles, aves, entre otros. Ammophila

arenaria es una hierba perene que domina dunas móviles (incluyendo antedunas

embriónicas y antedunas) a lo largo de la costa Europea. Por su fácil colección,

transplantación, propagación y adaptación a las dunas de arena, esta hierba es

comúnmente usada en Europa y mundialmente para propósitos de estabilización de

dunas. El afido de duna, Schizaphis rufula es una especie de herbívoro comúnmente

asociado a esta hierba a lo largo del rango de distribución de la planta huésped. Estudios

para ganar conocimiento acerca de las interacciones entre A. arenaria y S. rufula no son

solamente necesarios para entender los rasgos biológicos básicos de estas dos especies,

sino que son útiles para la creación de estrategias de manejo óptimas para ecosistemas de

duna. La meta de este estudio era estudiar la multiplicación de S. rufula en varios

genotipos de A. arenaria provenientes de diferentes localidades dentro del rango de

distribución natural de esta especie. También lo dirigimos hacia evaluar si S. rufula

prefiere los genotipos locales o alopátricos de esta hierba. Plántulas de Bélgica,

Inglaterra y Portugal fueron expuestas a una población de áfido colectado en Bélgica.

Luego del proceso de inoculación, se le permitió a los áfidos multiplicarse y alimentarse

en los diferentes genotipos de las plantas por 20 días. El número de áfidos fue utilizado

para generar una curva de crecimiento poblacional para cada combinación de áfido-

planta. La dinámica de crecimiento entre las poblaciones de A. arenaria fueron

comparadas usando un “one-way” ANOVA. Las cuatro combinaciones planta-herbívoro

revelaron diferencias significativas en la multiplicación entre las poblaciones, con una

reproducción de áfidos más alta en poblaciones de Bélgica (local) y de Wales, Inglaterra.

Por lo tanto, el origen de la población de la planta influencia la multiplicación de áfidos,

no obstante, no se descubrió correlación directa con el origen geográfico de la planta

huésped en esta prueba. Otras variables como rasgos específicos de la planta y defensas

deben ser evaluados con más detenimiento para determinar el mecanismo de selección

tras el patrón observado. Nuestro estudio indica que se debe tomar precaución al escoger

material vegetativo para propósitos de restauración en sistemas de dunas costeras debido

a los impactos potenciales en la fauna asociada.

x

ABSTRACT

Coastal dunes are large sand accumulations along the shoreline formed by sea currents,

surges, wind or vegetation. The vegetation provides dune stabilization, while creating

suitable habitats for a large number of organisms including insects, crustaceans, reptiles

and shorebirds. Ammophila arenaria is a perennial grass that dominates mobile dunes

(including both embryonic foredunes and foredunes) along the European

shoreline. Because of its easy collection, transplantation, propagation and adaptation to

sand dunes, is commonly used in Europe and elsewhere for dune stabilization

purposes. The dune aphid Schizaphis rufula is a common species associated with this

grass along the distribution range of the host plant. Studies to gain insights into the

interactions between A. arenaria and S. rufula are not only necessary to understand basic

biological traits of these two species, but can also be useful to guide optimal management

strategies on dune ecosystems. The goal of this study was to study the multiplication of S.

rufula on various genotypes of A. arenaria coming from sites within the natural

distribution range of this grass species. We also aimed to evaluate whether S.

rufula prefers local or allopatric genotypes of this grass. Seedlings from Belgium, United

Kingdom and Portugal were exposed to one aphid population collected in Belgium. After

inoculation, aphids were allowed to multiply and feed on different genotypes of the plants

for 20 days. Aphid numbers were used to generate a population growth curve for each

aphid-plant population combination. Growth dynamics were compared between A.

arenaria populations using a one-way ANOVA. The four plant-herbivore combinations

tested revealed significant differences in multiplication among populations, with higher

aphid reproduction on local (Belgium) populations and plants from Wales, United

Kingdom. Therefore, plant population origin does influence aphid multiplication;

nonetheless, no direct correlation with host plant geographic origin was discovered in this

assay. Other variables such as specific plant traits and defences must be further assessed

to determine the mechanism behind the observed pattern. Our study indicates that

caution should be taken when choosing plant material for restoration purposes in coastal

dunes due to the potential impacts on the associated fauna.

1

CHAPTER I

INTRODUCTION

Background of the problem

Dunes are large sand accumulations along the shoreline formed either by sea

currents, surges, wind or vegetation (Haslett, 2009). Certain plant species and animals

are adapted to dune conditions and colonize them as they form through saltation and

aeolian processes. These processes have been defined as large inputs of sand and active

wind displacement (Herrmann, Durán, Parteli, & Schatz, 2008). Generally, dunes are

found in an active or stabilized state. Dunes in an active state, also referred to as

dynamic, have loose sediments undergoing constant displacement, which alters its size,

form and position. On the contrary, stabilized or impeded dunes, are covered by

vegetation, which contributes to a much lower level of sand displacement, loss and

tendency of inland migration (DNER, 2010a; Haslett, 2009).

In Europe, cemented dunes, are the only natural means of shoreline

reinforcement, while in the tropics, coral reefs, thalassia beds and mangrove forests

provide additional coastal protection against tidal surges, hurricanes and hurricane-

generated waves. They also prevent storm waves from flooding inland higher elevation

zones along the coast (Miller, Thetford, & Yager, 2001).

Dune recuperation is a very slow process that occurs naturally over time. In the

occurrence of severe damage, management becomes imperative in order to accelerate

dune reconstruction. During recent years, dune restoration projects have been directed

towards the development of new reinforcement techniques, such as gate systems and the

2

identification of appropriate plant species for sand stabilization. The most common

approaches methods are sand fencing to enhance sand accumulation and planting of

native grasses for natural restoration and promotion of secondary succession (DNER,

2010a; Miller et al., 2001).

A major threat currently faced by dune systems, stems from large scale operations

that extract sand for construction purposes. Sand removal by unnatural causes

exacerbates the process of erosion and contributes to saline intrusion in fields and

aquifers that were once protected from the effects of rough seas (Valeiras, 2007). This

phenomenon was documented by both Valeiras (2007) and the Department of Natural and

Environmental Resources (DNER, 2010b) in Puerto Rico, most frequently in Isabela,

Hatillo, Camuy, Arecibo, Barceloneta and Loíza. Of these locations, the dune formations

at Isabela and Loíza contain the largest accumulation of sand on the north shore of the

island (DNER, 2010a). In Europe, sand is extracted from the continental shelf (water

depth < 60 meters (m)) every year, affecting innumerable coastal processes and marine

habitats, including the ocean sea bed, benthic organisms, and waves and currents which

alter sediment transport and accelerate erosion, accretion and coast retreat (Krause,

Diesing, & Arlt, 2010; Kortekaas, Bagdanaviciute, Gissels, Alonso-Huerta, & Héquette,

2010). The Baltic Sea in particular, which connects to the North Sea, contains various

sites for sand extraction that have been exploited for more than a century. The extracted

sand is used for industrial purposes, construction and beach nourishment, especially large

quantities of sand that are removed and used for coastal defense purposes. This process

of sand extraction from the active beach profile, known as draw-drown, causes a net loss

of available beach material (Kortekaas et al., 2010).

3

Rapid coastal development on the shoreline also contributes to the degradation

and destruction of coastal dune areas. Reconstruction and restoration of these systems

represents a challenging management task after the zone has been dominated by resorts

and high-cost residential complexes. New dunes, undergoing any restoration process,

will tend to be small in relation to pristine dune mounds that could reach up to 98 feet,

documented first in Puerto Rico before overexploitation. Restored dunes will likely

never be able to return to the typical linear formation that characterizes them naturally

(DNER, 2010b; Antunes do Carmo, Schreck Reis & Freitas, 2010).

Dunes are created and maintained naturally by the vegetation that covers them.

Vegetation associated with dune systems is generally located inland, above the upper tidal

zone limits (Lomba, Alves, & Honrado, 2008). The vegetation serves as dune

stabilization, while creating habitats for a large number of organisms that might include

insects, crustaceans, reptiles and shorebirds (Haslett, 2009). Plant colonizers or pioneers,

are herbaceous halophytes which can forage and are resistant to sand displacement, water

scarcity and high salinity. This type of vegetation is important because it traps and

compacts moving sand on the dunes (Acosta, Ercole, Stanisci, Pillar, & Blasi, 2007).

Some of these species provide shade, reducing the evaporation of moisture from the soil

surface and creating particular conditions for new species establishment. The extensive

root systems of plant species that colonize dunes hold sand in its place. Moreover, this

vegetation allows the dunes to continue accumulating sand over a long period of time,

contributing to its solidification. Vegetation assists trapping the sand particles, while

their deep fibrous roots provide stabilization (Lonard & Judd, 2011; Miller et al., 2001).

4

Sarre (1989) reported that the vegetation helps decrease the speed of wind near

the surface, and causes deposition of the sand being transported when it encounters the

vegetation. The presence of vegetation therefore decreases the rate of dune deflation

(Judd, Summy, Lonard, & Mazariegos, 2008). Among the vegetation that contributes to

sand accretion and coastal protection we can find sea oats (Uniola paniculata), bitter

panicum grass (Panicum amarum) and its variations and the American marram grass or

American beachgrass (Ammophila breviligulata), native to eastern North America along

the Atlantic Ocean and the Great Lakes coasts (Lonard & Judd, 2011; Miller et al., 2001).

Exclusively in Europe, Ammophila arenaria is a perennial grass that can be found

dominating mobile dunes, including both embryonic foredunes and foredunes (Lomba et

al., 2008). It is the most commonly used for this purpose because of its easy collection,

transplantation, propagation and adaptation (Antunes do Carmo et al., 2010).

Marram grass Ammophila arenaria (L.) Link is a dominant grass species of

dynamic coastal dunes and it is naturally distributed along all European coasts south of

latitude 63 degrees North (°N) (Huiskes, 1979). The species has been introduced in

several areas of the world for dune stabilization (i.e. East and West coasts of USA, South

Africa, Australia, New Zealand and Chile) where in some cases has become highly

invasive. Hilton, Duncan, and Jul (2005, p. 175 & 184) reported that “Ammophila

invasion of active dune systems […] is clearly associated with the dune forming

processes […] by stabilizing naturally mobile dunes and accelerating vegetation

succession.” The interactions occurring in the rhizosphere of this dune grass and the

aboveground herbivore arthropod community form one of the best documented cases of

5

the role of multitrophic interactions on plant community succession and dynamics (van

der Putten, Vet, Harvey, & Wackers, 2001; Zoon, Troelstra, & Maas, 1993).

Statement of the problem

Strong prevailing winds, usually coming from high-energy ocean swells, transport

massive quantities of particles and sediments that lead to the formation of dune-barriers

on the coast (Short, 2010). Specifically, Ammophila arenaria play an important role on

dune formation by its dune fixation capacity, trapping the sand blown by these winds.

Though it provides such an important ecological service, A. arenaria has been

documented as introduced and invasive across the world and furthermore, capable of the

displacement of entire native plant communities and drastically reducing their natural

habitat (Vandegehuchte, 2010a). Among the herbivore community associated with this

grass, we find the dune aphid Schizaphis rufula Walker 1849.

Globally, aphids are major insect pests, causing significant economic loss to

markets in the production of crops such as grains, vegetables, fruits, flowers and wood

(van Emden & Harrington, 2007). As documented by Vandegehuchte, de la Peña and

Bonte (2010b), S. rufula has been recently discovered in sand dune areas in Belgium,

Europe and is known to feed and live specifically on the leaves of A. arenaria grass.

Studies in the laboratory, demonstrates how yellowish-brown leaves can serve as an

indicator of aphid infestation on the plant, leading it to its death.

Currently, much is still unknown regarding the interaction between Schizaphis

rufula and A. arenaria (de la Peña, personal communication, April 2011). Given the wide

geographical range of distribution of Ammophila arenaria and the aphid S. rufula the

6

occurrence of genotypic variation and performance differ among the different non-

overlapping geographical areas (de la Peña, personal communication, April 2011).

Studies to gain insight in the interactions among the A. arenaria and S. rufula are

necessary to optimize management strategies on dune ecosystems.

Justification

Dune restoration and dune building is a common challenge for littoral areas under

natural and anthropogenic pressure. Changes in the system are often evaluated as a

whole, sometimes overlooking the importance of the interactions occurring in the

vegetation that geographically adapts to them. Plant associations within a (bio)

geographical area can serve as a basis for bioindication in monitoring and management of

coastal dune systems (Lomba et al., 2008). Acosta et al. (2007) reported how methodical

studies of the interactions occurring on plant communities adapted to coastal ecosystems

contributes to the understanding of variables such as dune morphology, vegetation

zonation, local adaptation, plant invasion and herbivore defences. A gap still exists,

however, in the understanding of adaptation to the local environment, herbivory and plant

traits in ecological terms (Bischoff & Trémulot, 2011).

Understanding the role of geographic variation and plant genetic differentiation in

the interaction between A. arenaria and its associated herbivores (i.e. dune aphid:

Schizaphis rufula) is necessary to understand the functioning of foredunes, improve dune

management and understand the invasive character of the species outside its natural range

(de la Peña, personal communication, April 2011).

7

Research Question

How is aphid performance on different Ammophila arenaria grass populations?

Goal

Evaluate the interaction between the dune aphid Schizaphis rufula and its host-plant

Ammophila arenaria: a comparison of insect multiplication on different host-plant

populations

Objective

Compare multiplication of the dune aphid Schizaphis rufula on different Atlantic

genotypes of Ammophila arenaria; to evaluate if this aphid S. rufula multiplies better on

sympatric populations than on populations from other geographic areas (allopatric).

8

CHAPTER II

LITERATURE REVIEW

Historical background

Dunes are large accumulations of sand deposited by wind and tidal surge on the

high-tide zone, on which environmental conditions favor the establishment of floristic

associations (Valeiras, 2007). Dunes, as permeable structures, generally protect the

shorelines from flooding, allowing the groundwater system to be recharged while

creating a barrier for saltwater intrusion (Carter, 1991). Among the impacts that affect

the dunes as critical habitat for numerous organisms, those that prevail are human

impacts such as destruction, sand extraction, excessive touristic and recreational

activities, coastal development and coastal erosion (Acosta et al., 2007; Valeiras, 2007).

Since the past 100 years, a new threat is affecting the world’s dune coastal

ecosystems. Little or no attention is being directed toward sea level rise and global

warming issues. Furthermore, studies investigating responses of dune vegetation to these

factors remains inconclusive. On its Fourth Assessment (AR4), the Intergovernmental

Panel for Climate Change (IPCC) reports how sea level is expected to rise 0.18 meters

(m) between the years 1985 and 2030 (IPCC, 2007). According to Carter (1991), sea

level rise directly affects the coastal processes that naturally stabilize the shoreline by

changing wave patterns, accelerating coast erosion, flooding, avulsion and altering

sediment fluxes. Coastal ecosystems worldwide are under threat due to these

phenomena. Areas under the most danger are located in low-lying countries like The

Netherlands and islands such as Puerto Rico, since their dune areas are on the shore and

9

are therefore, the first systems to be affected by changes offshore (Noest, 1991).

Currently, as a proactive measure against sea level rise and climate change, The

Netherlands are dredging more than 18 million cubic meters of sand from the bottom of

the North Sea and pouring it onto the new coast band, creating a new dune system,

broadening the beach and gaining territory. Although the coast is safe under current sea

level conditions, this technique is being developed as a management strategy to protect

the coast at the levels projected fifty years from now (Rijckaert, 2009).

As mentioned before, natural vegetation on dune ridges is crucial for the

conservation of the dune morphology as the vegetation traps blowing-sand, protecting the

shoreline from erosion (Acosta, Ercole, Stanisci, Pillar & Blasi, 2007). It is believed that

Ammophila arenaria, as a C3 photosynthetic plant that succeeds within moderate sunlight

intensity and moderate temperatures, will be directly affected by global warming. These

plants, already identified as invasive species in some locations, will tend to grow faster as

temperatures continue to rise and groundwater and CO2 patterns are altered in their

respective cycles (Carter, 1991; Ricklefs, 2008a).

The dune aphid Shizaphis rufula is a common species associated with Ammophila

arenaria grass along the distribution range of the host plant. Studies to gain insight into

the interactions between A. arenaria and S. rufula are necessary not only to understand

basic biological traits of these two species but can be useful to guide future management

strategies on dune ecosystems. S. rufula is a specialized herbivore species known to live

and infest the leaves of A. arenaria. However, it was neither discovered nor described in

Belgium until 2007, after a field survey conducted by Vandegehuchte, de la Peña &

10

Bonte (2010c). It can be found across Europe, including Britain, Corsica, Denmark,

Finland, Germany, Ireland, Poland, Sicily, Sweden, the Netherlands and Ukraine.

Little is still known about S. rufula’s dynamic and it is thought that, A. arenaria’s

displacement may affect the aphid presence on the grass. The aphid seems to prefer

young, vital shoots (seedlings), and in addition, it has recently been discovered that

belowground interactions also affects its performance (Vandegehuchte et al.; 2010c).

Conceptual/theoretical framework

a) Ammophila arenaria

Ammophila arenaria is known to be the major dune-forming grass. The Gauls, a

group from ancient Western Europe (modern North Italy, France, Belgium and South

Netherlands) were the first to utilize this species of grass. They adapted dune seeding

programs to protect their capital cities from being flooded with sand in 600 B. C. (Green,

1965). Sand fixation was recorded in 1316 in Germany (Withfield & Brown, 1948)

where Ammophila was used to stabilize main dune complexes, and this practice was

reported in the 17th

and 18th

centuries as well (Vandegehuchte, 2010a).

Ammophila arenaria is native to coastal areas and abundant on mobile and fixed

dunes where vegetation has developed, creating suitable substrate. Among the most

common subspecies we can find the North American spp. breviligulata, native from sand

dunes along the Atlantic coast of North America, the Great Lakes and also found in

Newfoundland. It is believed that spp. breviligulata was introduced on the British Isles

around 1953 (Huiskes, 1979).

11

Atlantic populations of Ammophila arenaria spp. arenaria can be found

throughout the coast of the North Sea, the Baltic and the Atlantic to northern Portugal.

On the other hand, Ammophila arenaria spp. arundinacea ranges from central to southern

Portugal, the Mediterranean and the Black Sea, being defined as a Mediterranean

population (Huiskes, 1979).

A. arenaria species are classified as perennial, meaning that they can grow and

produce inflorescence from the same root over the course of several years. Perennials

can die off-season and grow again bigger and stronger after this cycle (Alderson, 2012).

Specifically for Ammophila, growth is slower in winter, while the leaves start growing

vigorously during spring and summer, dying in autumn (Huiskes, 1979).

Clonal spread, or asexual reproduction developed by interconnected rhizomes, is

more successful for Ammophila’s reproduction than seedling dispersal. Dispersed seeds

can desiccate easily, or the transport can be affected by sand burial and erosion, not

allowing the establishment of the population. In some cases, when reproduction is

successful, a single genet can age over a hundred years (Huiskes, 1979).

It is common to find Ammophila arenaria along the Belgian coast of Europe;

specifically in the north-west geographical area defined as the coastal plains. North-west

flat coastal plains are characterized by dunes and polders; land areas close to or below sea

level that have been reclaimed by water. Strong prevailing winds, coming from high-

energy ocean swells specifically occurring in the North Sea, transport massive quantities

of particles and sediments that lead to the formation of dune-barriers on the coast (Short,

2010). These winds are responsible for sand accretion and dune formation on site,

propitiating the establishment of this grass.

12

Ammophila arenaria can also be found naturally distributed along all European

coasts south of latitude 63°N. The two subspecies, Ammophila arenaria spp. arenaria

and Ammophila arenaria spp. arundinacea, can be found along this range. The former

on the north range, specifically on atlantic dune systems and the latter from Portugal

southwards along the Mediterranean and Black Sea coasts (Huiskes, 1979;

Vandegehuchte, 2010a).

b) Genetic diversity and local adaptation of Ammophila arenaria

Populations are constantly changing, and in nature, those changes are generally

determined by size, distribution, structure and genetic composition of the population in

question. Limiting factors within populations are commonly dictated by the availability

of resources, but occasionally, intraspecific interactions can also contribute to changes in

the genetic composition of these populations, confining them to different geographical

ranges. It is known that even at small geographical scales, plant species have

demonstrated notable genetic differentiation (Ricklefs, 2008b).

The adaptation of living organisms to their environment is a function that assures

the existence and continuation of the species. Established by the Natural Selection

Theory, organisms should possess the genetic capability to adapt to the changing

environment, while passing critical genetic information on to their offspring to prevent

extinction. Evolution traits can also be referred to as evolutionary adaptations, and in

addition to gene flow, these are responsible for the introduction of new genes to

populations from the same species (Mader, 1990; Ricklefs, 2008c).

13

Adaptation of plant species to their local environment is a well-documented

phenomenon, while little is known about the selection mechanisms of its associated

organisms, (i.e. herbivores to their host-plant). These kinds of interactions are important

to management projects because they influence the outcomes of treatments like the

introduction of non-local genotypes for restoration or the re-vegetation of areas of

concern such as dune systems (Bischoff et al., 2011).

De la Peña, Bonte, and Moens (2009) reports how population differentiation and

local adaptation on plants can be triggered by the selection pressure exerted by

herbivores. Traits like herbivory defences, as an example, continually change as the plant

is subjected to herbivore pressure. Plant defences against herbivory or host-plant

resistance (HPR) can provoke the plant to react to functional traits, developing survival

strategies such as avoidance of herbivores by changing growth patterns and location.

Change of location as a response of HPR, can directly contribute to the evolution of the

plant dynamic, such as the developing of different population genotypes. Eventually,

HPR can determine the geographic structure of the population and its herbivore

community (de la Peña et al., 2009; O’neal & Hodgson, 2008). This geographic

structure, in combination with the herbivore selection pressure, is the variable responsible

of genetic differentiation and ultimately, local adaptation of different plant populations

(de la Peña et al., 2009).

Ammophila arenaria dispersal mechanism is primarily clonal growth. The word

“clonal” in the term “clonal growth” implies that the individuals will descend from the

same “parent”, bearing the same genotype (Ricklefs, 2008d). This type of dispersal

represents low intraspecific gene flow among populations, “creating large genetic

14

distances between geographically separated populations” concludes de la Peña et al.

(2009). Meanwhile, Rodríguez-Echevarría, Freitas, and van der Putten (2008, p. 125+)

explains how “the molecular characterization of A. arenaria populations indicate that

there are marked genetic differences between populations separated by large geographical

distances.” Nonetheless, more studies needs to be performed to support these statements.

A more in-depth research study by Rodríguez-Echevarría et al. (2008) indicated

that populations from Belgium, England, France and Portugal presented minimal genetic

diversity, while the lowest diversity values were found on the Netherlands and Southern

Portugal populations. It must be mention that populations from England, Wales and the

Netherlands were classified as Ammophila arenaria arenaria (Tutin et al., 1980), while

populations from Portugal and Mediterranean France were from the southern subspecies

Ammophila arenaria arundinace (Tutin et al., 1980), which still indicates genetic

differences among populations. The study suggest how even when genetic differentiation

can still be inconclusive, results are not always correlated with geographical distance

(Rodríguez-Echevarría et al., 2008).

c) Aphid Schizaphis rufula growth dynamic

When working with dune aphid Schizaphis rufula, herbivore of A. arenaria, the

collection of just a few individuals results enough, since it is a specialist aphid species

which mostly multiplies by apomictic parthenogenesis. Parthenogenesis, as defined by

Ricklefs, 2008d, (p.162) is “the asexual female reproduction without fertilization by

male gametes, usually involving the formation of diploid eggs whose development is

initiated spontaneously.” It is believed that for Aphidoidea, S. rufula’s superfamily, this

reproduction system evolved in the Triassic period. Parthenogenetic females used to lay

15

eggs, similar to other modern parthenogenetic species, but they developed the ability of

viviparity, or giving birth to live offspring that have developed within the mother’s body.

Parthenogenesis provides S. rufula the capability of rapid dispersal and plant infestation

(Blackman & Eastop, 2007).

Aphids can be morphologically recognized by their piercing-sucking mouthparts,

which penetrate the phloem tissue of herbaceous plants in order to extract sugars and

other nutrients. Mostly, they can be found on the undersides of leaves and stems.

Densities can range from low to high, creating persistent colonies in approximately 2

days, multiplying the size of the population up to hundreds of individuals. Aphid

infestation affects plant fitness, including height and photosynthesis and it is common to

observe them utilizing the cauda or tail to remove the honey-dew produced from their

anus, while feeding. This honey-dew, or sugary excretions, makes the plant prone to

mold, therefore having a debilitating effect on it (Tilmon, Hodgson, O’neal, & Ragsdale,

2011; Blackman & Eastop, 2007).

Like every individual that compose it, any population will dynamically grow until

achieving an equilibrium point. The equilibrium point or the carrying capacity of a

population is achieved when densities increase until the maximum number supported by

the habitat is reached. It is believed that after reaching its capacity, population-crash

follows. This concept was made widely popular by the economist Thomas Robert

Malthus in 1798 (Smith, 1966). Aphid’s population growth can usually be represented

with the SIGMOID method, an S-shaped curve which describes growth of the population

over time. It is common to utilize this method under controlled experimental systems

where populations are kept and growth under confinement (Colinvaux, 1986).

16

d) Management strategies and conservation

A clear understanding of the Ammophila system is crucial for restoration projects

all over the world, especially for coastal conservation and regeneration projects. When

introducing a grass for sand compaction processes it is necessary to know exactly where a

population originates and the location where the sample seeds where collected. Usually,

plant material should be collected locally, but in some cases non-local plants are

introduced. There is limited information available related to the introduction of non-local

Ammophila populations. Local plant material should be preferred over imported

material, to provide a bigger genetic pool that could help optimizing transferred grasses

and enhance resistance (Rodríguez-Echevarría et al., 2008).

Case studies

a) Evidence of population differentiation of Ammophila arenaria dune grass and its

associated root-feeding nematodes

The entire arrangement of plant populations and communities within the

landscape can be determined by soil composition, occasionally resulting in local

adaptation of those communities. De la Peña et al. (2009) worked with nematodes,

parasitic unsegmented roundworms from different species and geographical locations

throughout Europe. Nematodes can affect soil dynamic and consequently, the nutrient

cycle and availability. Pratylenchus brzeskki and Pratylenchus dunensis are two species

of endoparasitic nematodes that can be found associated with A. arenaria in coastal dune

ecosystems throughout Europe. Sixteen plant-herbivore interactions between these

nematodes and the Ammophila arenaria grasses coming from the same nematode-

17

location were studied. Belowground-herbivore response information, in term of growth

and multiplication were collected. In most of the cases, it is expected from the plant-

herbivore combination coming from the same location to adapt to its local conditions.

However, variation can occur, and it was found that nematodes growth development on

sympatric host was adverse, meaning success of local combinations should not be

assumed. Nematodes also had a negative effect on plant biomass growth, and overall, the

outcome among combinations ended up being case-dependent.

b) Aphid-transmitted viruses: use of barrier plants as a management tool

Aphids are known to function as major virus vectors, specifically of the “aphid-

borne non-persistent transmitted viral diseases” (ABNPV) which cannot be controlled by

insecticides. A study done by Hooks and Fereres (2006) using barrier plants as

management tools, explains that aphid virus transmission accounts for 50% of the 600

known viruses transmitted by invertebrates. Factors such as host-plant selection, visual

stimuli and color attraction influence on the aphids preference to inhabit and feed on a

plant. It is believed that the transmission of viruses by aphids can be controlled by plant

resistance that might have been developed genetically. Power (1991), reported that even

when aphids were abundant on different oat habitats, incidence of the transmitted Barley

yellow dwarf virus (BYDV) was consistently lower on genetically diverse oat plantings,

reducing virus transmission. More in-depth studies of the environmental parameters that

limit aphid’s effects on crops are still needed.

c) Population genetic structure of economically important Tortricidae (Lepidoptera)

In a study by Timm, Geertsema, and Warnich (2010), the population genetics

structure of the codling moth C. pomonella, the litchi moth Cryptophlebia peltastica, the

18

macadamia nut borer Thaumatotibia batrachopa and the oriental fruit moth G. molesta

were studied. The analysis of population genetics can provide insights of the structure

and arrangement of these populations. DNA extractions were obtained from the

specimens and analyzed using the amplified fragment length polymorphism AFLP. It

was found that all of these four economically important pests from the Tortricidae family

have the same genetic structure, not only regional but it can even be found on isolated

populations along a local geographical setting. It is suggested that this outcome was a

result of limited dispersal ability, which in this case, can be a positive response in relation

to pest management strategies. Timm et al. (2010) concludes reporting how insecticide

use and anthropogenic movement could also be limiting these populations, where in most

of the cases they act sedentary and choose to stay near their habitat or orchard.

Legal frame

In this study, since our sites and related organisms are directly linked to the

European coastal zone, we take into consideration, the legal dictations of dune ecosystem

management in Belgium, and more generally Europe. The grass of interest, Ammophila

arenaria, can be found dominating dynamic coastal dunes, naturally distributed along all

European coasts south of latitude 63 degrees North (°N) (Huiskes, 1979). Schizaphis

rufula, A. arenaria’s associated herbivore, has recently been discovered on sand dunes in

Belgium, Europe and is known to feed and live specifically on the leaves of this grass

(Vandegehuchte, de la Peña, & Bonte, 2010b).

19

Model Law on Sustainable Management of Coastal Zones and European Code of

Conduct for Coastal Zones (Council of Europe, 2000).

A group of Specialists on Coastal Protection, under the order of the Committee of

Ministers of the Council of Europe, met for the first time in 1996 where they discussed

how a high amount of technical and scientific research had been performed in the field.

Still, it implied the need of integrated management and planning of coastal areas, the

definition and implementation of these concepts and instruments for sustainable coastal

management. Therefore, the Council of Europe, in efforts with the European Union for

Coastal Conservation (EUCC) and the United Nations Environment Programme (UNEP)

proposed to take action and prepared drafts for the code of conduct and a Model Law on

coastal protection.

The code of conduct draft needed to include recommendations, principles and

defined rules for local, regional and national authorities, developers, coastal engineers

and users. Likewise, the Model Law needed to define the concept of integrated

management based on sustainable development, while establishing guidelines and

instruments for it appropriate application. As a result, it was expected that the

preparation of these documents led to, either amend legislation or the creation of new

laws and acts on coastal zones, land use planning, conservation and decision-making.

The Council of Europe Ministers adopted the document on April 1999. It is

intended to provide management guidance strategies to the local authorities and also, to

the commercial sector. Assessment for the management of direct threats such as habitat

destruction and indirect threats such as habitat degradation and health impacts on wildlife

and humans are included in these documents (Council of Europe, 2000).

20

I. Model Law on Sustainable Management of Coastal Zones

a) Definitions

Title 1, Article 1 - First of all, the Law starts defining the two most common terms

used throughout the document. The coastal zone is defined as “a geographical area

covering both the maritime and the terrestrial part of the shore, including salt-water ponds

and wetlands in contact with the sea”. The document aspire all territorial waters and

public territories bordering seas and oceans to be covered by this law, including estuaries

and deltas.

Article 2 - Integrated management is defined as “sustainable development and use

of coastal zones which takes into consideration economic and social development linked

to the presence of the sea while protecting landscapes and the coastal zone’s fragile

biological and ecological balances for present and future generations”.

Title 2, Article 8 - Among the principles stated in the law concerning directly to

threatened ecosystems such as dune ecosystems, it is suggested that fragile areas and

threatened ecosystems (covered in Title 12) should be protected, restricting access, in

some cases.

b) Dunes and vegetation cover

Title 9, Article 48 – “Vehicular traffic, movement and parking of motor vehicles

and mountain bikes on dunes and beaches shall be prohibited, except in areas and trails

provided for that purpose”.

Title 12, Article 60 - “Dunes shall be classified as sensitive zones, or as nature

reserves. Access may be restricted and special soil stabilization measures shall be taken

using biological methods and preserving herbaceous or tree cover.”

21

Title 13, Article 65 - “Parts of coastal zones where the soil and coastline are

fragile or prone to erosion shall be classified as critical zones. Access may be prohibited

and specific stabilization measures shall be taken. Buildings and other structures,

recreational facilities, roads and car parks shall be prohibited in these areas”.

Article 66 - Coastal woodlands shall be classified in order to prevent their

destruction and protect their plant cover and its soil-stabilizing role. Cutting down or

uprooting plants which also help to stabilize soil shall be prohibited. However, under

certain circumstances which may benefit the environment and in furtherance of nature

conservation objectives, destabilization and uprooting of may be allowed as a form of

dynamic management.

Article 67 - Excavation and sand removal should be regulated. “Submarine

prospective and excavation for mining, historical or archaeological purposes and the

extraction of sand or gravel from the fringe of the coastal zone or from watercourses shall

require prior administrative authorization. Such authorization shall be preceded by an

Environmental Impact Assessment and by an opinion from the scientific committee

mentioned in Article 28”.

c) Management and public participation

The public should be included and also, participate in the creation of any

decision-making process or draft of any concerning coastal zones before any plan is

finally adopted. Methods include writing or at public hearings, and their opinions should

be considerate, while they have the right to appeal in court. National and regional

authorities should work together to create and enforce coastal and marine reserves and

furthermore, to develop international agreements.

22

For this purpose, the Pan-European coastal, ecological and research centre

networks were identified to locate significant diversity and to help designate protected

coastal and marine areas. In addition, it provides a platform for the exchange of scientific

data and information to use as an instrument for public awareness, integrated

management and sustainable use of coastal zones.

II. Analogous laws, regulations, and orders for the maritime-terrestrial zone and dune

ecosystem management in Puerto Rico

In Puerto Rico, the general policy declares “to avoid the activities that can cause

the deterioration or destruction of the natural systems that are critical for the preservation

of the environment, such as... dunes" (DNER, 2008, p.30.3).

a) Law number 132 of June 25, 1968, Sand, gravel and stone act (Ley de arena,

grava y piedra) (DNER, 2008).

b) Law number 241 of August 15, 1999, New wildlife law (Nueva ley de Vida

Silvestre).

c) Regulation number 6916, Regulation for the extraction, excavation, removal

and dredging of earth crust components (Reglamento para regir la extracción de

materiales de la corteza terrestre) (DNER, 2008).

d) Regulation number 4860, Marine spatial planning guidelines for the

submerged lands of Puerto Rico (Reglamento para el aprovechamiento, vigilancia,

conservación y administración de las aguas territoriales, terrenos sumergidos y la

zona marítimo terrestre.

e) Planning regulation number 13 (amended in 2002), Special flood hazard areas

(Reglamento sobre áreas especiales de riesgo a inundación) (DNER, 2008).

23

f) Planning regulation number 17, Zoning regulation for the coastal zones and

the access to beaches and coasts of Puerto Rico (Zonificación de la zona costanera

y de accesos a las playas y costas) (DNER, 2008).

g) Administrative order number 2-93 (OA-2-93), To establish the public policy

on the conservation of the sand resources in Puerto Rico (Para establecer política

pública sobre la conservación de los recursos de arena en Puerto Rico) (DNER,

2008).

24

CHAPTER III

METHODOLOGY

The goal of this research was to evaluate the interaction between the dune aphid

Schizaphis rufula and its host-plant Ammophila arenaria by making a comparison of

insect multiplication on different host-plant populations. We established the objective of

analyzing the multiplication of dune aphid Schizaphis rufula on different atlantic

genotypes of Ammophila arenaria grass to evaluate if dune aphid S. rufula multiplies

better on its local Ammophila arenaria population than on Ammophila populations from

other geographic areas.

The study area was located in Ghent, Belgium and for the experimentation, the

system was replicated in the Laboratory under controlled conditions. Support for

materials and internship was provided by the José Jaime Pierluisi Foundation and the

CES-PRIDCO – P uerto Rico Council on Higher Education fellowships, altogether. For

Ghent University acceptance letter, please refer to Appendix 2.

Seeds handling

Experimental design: Acquisition

Three Atlantic and one Mediterranean population were used for this research. The

subspecies Ammophila arenaria spp. arenaria was defined as the “local” variation, with

two populations from Belgium and one from the United Kingdom. One population of

Ammophila arenaria spp. arundinacea, from Portugal was cultivated, defined as

Mediterranean.

25

We performed a laboratory replication of the grass-dune aphid system, using

samples from both ranges. Therefore, we utilized seedlings from:

a) De Panne, Belgium (Local - Atlantic)

b) Westende, Belgium (Local - Atlantic)

c) Ynyslas, Wales, United Kingdom (Atlantic)

d) Comporta, Portugal (Mediterranean)

De Panne and Westende can be found on the north-west coast of Europe, all

within an approximate 30 kilometer radius of one another. Ynyslas can be found west of

Belgium on the west coast of the United Kingdom, while the Comporta population is the

only population sampled from the Mediterranean, which is south of the U. K., on the

Portugal’s west coast near Spain.

Sterilization

Surface sterilization of the A. arenaria seeds was performed following the Sauer

and Burroughs Method (1986). Seeds were submersed in 4% household bleach solution

for 5 minutes, rinsed 10 times with water, submersed in 10% ethanol for 5 minutes and

then rinsed another 10 times with water. This sterilization method effectively eliminates

horizontally transmitted fungi that could otherwise colonise the young seedlings.

Transplanting

Seeds were subsequently germinated at a light regime of 9/15 hours dark/light in

plastic trays filled with 190 cubic centimetres (cm3) of sterile dune sand that was

26

autoclaved for 1 hour at 120 degrees Celsius (°C) and 1 atmosphere (atm). The sand was

saturated with water. Twenty-four days after the seeds were placed on the sand to

germinate, seedlings were selected and transplanted into 20 1-liter (l) plastic pots filled

with 550 grams (g) of autoclaved dune sand and placed under a 9/15 hours dark/light

regime. Pots were covered with perforated plastic caps to maintain moisture and allow

sufficient ventilation. Moisture level was reset to near saturation daily. Pots were

randomised on the growth bench. Plants were watered every two days and fertilizer

(Hoagland’s nutrient solution) was applied once every two weeks. This process was

performed until seedlings grew enough for them to be able to resist aphid treatment.

Aphid handling

For this research, aphids were allowed to reproduce parthenogenically, multiply

and become adults on Ammophila arenaria host-plants before being utilized as treatment

for the controlled experiment. Aphids were obtained from a laboratory culture that was

propagated from one wild individual collected from the Westhoek Nature Reserve in De

Panne, Belgium. Plants were inoculated with one adult aphid on day 92 after the

seedlings were first planted in the pots. Left to reproduce parthenogenically on the plant,

aphids were counted daily to provide a population growth curve for each replicate.

Previous experiments with this system have shown that populations usually grow to a

peak density after which aphid numbers rapidly decline (adapted from de la Peña &

Vandegehuchte, 2010).

27

Data analysis

Values obtained were checked for normality and heteroscedasticity, which

determines if variance in the group was the same among the data identified by a normal

distribution. Aphid numbers were used to generate a population growth curve for each

replicate. S. rufula growth dynamics were compared between A. arenaria populations

using a one-way ANOVA.

28

CHAPTER IV

RESULTS AND DISCUSSION

The principal objective of this research was to evaluate interaction dynamic of

dune aphid Schizaphis rufula on different Atlantic genotypes of Ammophila arenaria; to

evaluate if S. rufula multiplies better on sympatric populations than on populations from

other geographic areas (allopatric). The necessity of the research derives from the lack of

knowledge about the genetic diversity of Ammophila arenaria grass populations and S.

rufula’s adaptation to them. The recent discovery of the association of this specific aphid

species with the grass has triggered numerous questions regarding selection mechanisms,

local adaptation, genetic traits, above-belowground herbivory and plant defense.

For this specific research, aphids were left to reproduce parthenogenically and

were counted daily to collect multiplication data (Table 1). After 20 days of aphid

infestation on Ammophila seedlings from 4 different plant populations, daily figures for

individual plants were gathered. Table 1 demonstrates quantification dates, aphid

presence and aphid quantity for every plant; standard deviation of aphid numbers is also

represented.

As discussed in Chapter II, like every individual that compose it, any population

will dynamically grow until achieving an equilibrium point. The equilibrium point or the

carrying capacity of a population is achieved when densities increase until the maximum

number supported by the habitat is reached. It is believed that after reaching its capacity,

population-crash follows (Colinvaux, 1986). It is evident that aphid numbers

exponentially grew for every population, achieving the equilibrium point around day

29

fifteen. After increasing to its maximum supported density, populations declined and

plants were uprooted. Aphid numbers were used to generate a population growth curve

for each replicate (Figure 1). S. rufula growth dynamics were compared between A.

arenaria populations using a one-way ANOVA.

The 4 plant-herbivore combinations tested revealed significant differences among

populations, with preliminary results demonstrating more successful aphid reproduction

on sympatric (De Panne, Belgium) grass populations. Nonetheless, aphid multiplication

on plants from Wales, United Kingdom overlaps with Belgium aphid numbers in a

specific time lapse (Figure 1). If we take this into consideration, we can conclude that,

overall, S. rufula performed better on local or less distant populations, compared to

populations from Portugal (Vandegehuchte, de la Peña, Breyne, & Bonte, 2011;

Vandegehuchte, 2010a). However, it would have been expected that figures from

Westende, Belgium would also overlap with figures from De Panne since it is the nearest

site geographically, separated by only 15 kilometers (km). This result implies how plant

material origin plays a role for the occurrence of S. rufula and also, how the outcomes

were strongly case-dependent.

No specific support for local adaptation of S. rufula was discovered with this

study. Comparatively, on a study by van der Putten, Yeates, Duyts, Schreck, Reis &

Karssen (2005), with different populations of Ammophila arenaria established outside

their native range and introduced in USA, South Africa, Australia and New Zealand, it

was found that plants supported a comparable number of root-feeding nematodes.

Suggestions have arisen about how some species of A. arenaria herbivores (i. e.

endoparasitic nematodes) can be considered as generalists rather than specialists, which

30

lead us to question the adaptability of these species to A. arenaria, despite geographical

location. At the same time, the invasiveness of Ammophila arenaria must be taken into

consideration, as this study clearly presents the grasses’ capacity to withstand above and

belowground herbivory outside of its native range, all the while establishing successfully

(Vandegehuchte, 2010a).

For this specific research, no direct correlation with host-plant geographic

location was discovered (Figure 2). A bigger seed pool from an extended geographical

range could have provided the possibility to determine a correlation assay. Rodríguez-

Echevarría et al. (2008) discussed how there is a necessity to perform research outside the

native range of Ammophila, because there are previous studies (i.e. Gray, 1985) that

suggest how there is ecological variation among populations, but this remark has to be

still tested at a continental scale. Results for this particular study suggested that

“European populations of A. arenaria are genetically diverse and that these genetic

differences are not always correlated with geographic distance” (Rodríguez-Echevarría et

al. 2008, p. 125). In further support of this statement, Vandegehuchte, de la Peña, and

Bonte (2011a) and Vandegehuchte (2010a) discussed how aphids and nematodes could

clearly distinguish between different Ammophila arenaria plant populations.

Conservation issues also arise from this complex scenario, if we take into consideration

that different plant genotypes will support different invertebrate species, therefore, the

interactions occurring in the rhizosphere of Ammophila can indirectly affect the whole

coastal ecosystem and its biological structure.

31

CHAPTER V

CONCLUSIONS AND RECOMENDATIONS

General conclusions

This study evaluated and compared the multiplication of the dune aphid

Schizaphis rufula on sympatric and allopatric populations of the European beachgrass

Ammophila arenaria. Ammophila arenaria has shown to be a successful dune

compacting grass since 1316 (Withfield & Brown, 1948), with rapid establishment

capability and the capacity to function as a multifunctional study system for above-

belowground herbivory. Other selection factors such as adaptation mechanisms and

herbivore defense can also be tested. Despite its invasive characteristic, Ammophila

arenaria has demonstrated proper fulfillment of an ecological service by sheltering an

entire ecosystem - serving as a living skeleton by providing habitat for a diverse

ecological community (i. e. herbivores).

The 2007 discovery of the dune aphid Schizaphis rufula on A. arenaria grass in

Belgium has triggered multiple research questions, the answers of which could

potentially end up addressing management issues for dune ecosystems worldwide. After

analyzing the results for the multiplication behavior of S. rufula on different population

genotypes of A. arenaria, both entomologists and environmental managers should be

concerned about the possibility of S. rufula successfully colonizing other geographic

areas outside of Europe. Aphids in general, have long been known as pests of cereals and

grasses, most of them tolerant to modern pesticide treatments (van Emdem & Harrington,

32

2007). S. rufula’s potential to expand outward from its native range should not be

underestimated.

A recent study by Meadows (2011) documented not only how “noxious” invasives

like Ammophila arenaria are dominating the interiors of California, but describes how the

grass is opportunistically utilizing its traits and the changes in climate to expand its range.

Ammophila takes advantage of its light-capturing efficiency and has emigrated into cooler

ecosystems, such as the north coast and mid-elevation mountains; areas richest in native

grasses, and previously free from exotics. As if the invasion was not enough of a

concern, A. arenaria shelters the deer mouse (Peromyscus maniculatus), which feeds on

the seeds of endangered Lupinus tidestromii, the Californian coastal lupine. This is a

recent example of the negative effects exotics can exert on the environment, especially,

on those ecosystems undergoing dynamic and constant change (Meadows, 2011).

Limitations

The methodology of this research was performed under controlled laboratory

conditions. Hence, life cycle and growth dynamic of Schizaphis rufula was easier to

understand and assess. However, performing similar methodology in-situ, on the

different A. arenaria’s populations geographical locations sites could have extended not

only analysis and results, but my understanding of the interactions occurring at each site.

The action of performing the research under laboratory conditions and not on the

European dune ecosystems per se, limited the findings and insight of the results. These

limiting factors have to be taken into consideration.

33

Recommendations

In terms of the use of Ammophila arenaria as the preferred vegetation material for

dune fixation and coastal dune protection, caution should be taken when choosing non-

local populations for restoration purposes. Local material should always be the primary

option, since even the use of slightly geographically separated populations could have a

significant detrimental effect on the local invertebrate community, leading to the non-

equilibrium of the ecosystem. Often, dune ecosystems are evaluated from a macroscopic

perspective, without assessing minor changes in the microscopic ecosystem functions that

could also have impacts on species aside from the “indicator species.” Interactions

within the rhizosphere of Ammophila arenaria are so complex, that they can affect the

whole plant, while at the same time, these biotic interactions could involve ecosystem

costs (Vandegehuchte , 2010a).

In terms of entomological research, other variables such as specific plant traits

and defences must be further assessed to determine the mechanism behind the observed

pattern (Figure 1) and investigate if it could have possibly affected the analysis. As an

example, we believe that host-plant resistance (HPR) has proven to be successful in

deterring aphids due to physical and chemical factors of plant tissue that may interfere

during probing (stylet penetration) (Goussain, Prado, & Moraes, 2005). Also, we must

take into consideration the abrasive characteristic of grasses from the Poaceae family,

which can function as primary defense that deters feeding and reduces foliage

digestibility, affecting herbivore performance (Massey & Hartley, 2006).

One of the principal reasons this research was possible, as wells as several other

investigations of Ammophila arenaria systems in Europe, stems from a rigorous legal

34

frame (Council of Europe, 2000). In Puerto Rico, simple management tasks such as

charges against irresponsible citizens and petitioning for stricter protection of coastal

ecosystems become an uphill battle. Meanwhile, a very different system, Europe’s Model

Law on Sustainable Management for Coastal Zones and the Code of Conduct for Coastal

Zones, could serve as a model for our legal frame. Europe has a long history of

managing coastal erosion, protection and land reclamation (i. e. the Black sea, the

Mediterranean sea and The Netherlands land reclamation battles) (Pranzini & Williams,

2012). Protection of Belgium’s dune ecosystems date back to the 1980’s and has shown

to be beneficial, not only environmentally but socio-economically.

The recommendations that could be derived from this research emphasize the use

of the legal frames of other continents (in this case Europe) as examples to enforce Puerto

Rico’s analogous laws, regulations and orders (see Appendix 6 & 7). We are losing

coastal and marine ecosystems at a very rapid rate and the anthropogenic pressure they

are subjected to accelerate the impacts that could eventually lead to the total destruction

of the natural resources that compose them. Taking a step forward to accept that our

environmental management system lack enforcement, understanding and support from

our community is key to minimize and change the detrimental scenario we are currently

facing. Involving the community in hands-on experiences and research findings so they

can relate to conservation efforts is one way that could possibly enhance the creation of

action-oriented techniques. Providing education and actively engaging our community in

projects that promote a sustainable shoreline, could positively impact our Island. I trust

that, though this research presents a small element in a more integrated project, it could

35

function as a motor for the visualization of a different management approach for the

Puerto Rican coastal dune ecosystems.

In the 1970’s and 1980’s, Puerto Rico’s dune ecosystems were healthy and

functioned as primary coastal defense for the north shore (DNER, 2010b). Today, the

Isabela dune systems are barely an example of what used to sit in their place. This

deprives not only our generation from the opportunity of identifying and assessing the

diversity of our dune ecosystems, but our children may also be prevented from

understanding the components of healthy coastal ecosystems if degradation persists as it

is.

With this research, I intend to provide not only methodology for the replication of

this study, but also the inspiration to start a movement that could positively mobilize

environmental agencies and environmental managers into gaining insight about the plant-

insect interactions occurring on the grasses that compact sand dunes around the island; an

initiative that could provide enough relevant scientific information to support the

enforcement of legal measures and policies that protect our coastlines.

36

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Antunes do Carmo, J., Schreck Reis, C., & Freitas, H. (2010). Working with nature by

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Bischoff, A., & Trémulot, S. (2011). Differentiation and adaptation in Brassica nigra

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Carter, R. W. G. (1991). Near-future sea level impacts on coastal dune landscapes.

Landscape Ecology, 6(1/2): 29-39.

Colinvaux, P. (1986). Sigmoid growth in laboratory populations. Ecology. Canada: John

Wiley and Sons.

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European code of conduct for coastal zones. (Nature and Environment Series No

101, ISBN 92-871-4152-5). Council of Europe Publishing.

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41

Tables

42

Table 1.

Daily populations of aphids on individual plants

Dates Average

No. of Aphids Std Dev of No. Aphids

Count of No. Aphids

21-07-2011 1.4333 1.8445 60

CP 1.5833 1.8809 12

DP 1.0833 1.6765 12

ON 1.6667 2.2293 12

WB 1.5000 2.0671 12

YW 1.3333 1.5570 12

22-07-2011 3.4333 3.1211 60

CP 4.1667 3.6639 12

DP 3.0000 3.3845 12

ON 2.5833 2.2747 12

WB 3.9167 2.5746 12

YW 3.5000 3.7050 12

23-07-2011 4.5667 3.9931 60

CP 4.6667 3.2004 12

DP 4.0833 4.3788 12

ON 3.2500 2.6328 12

WB 5.7500 4.0704 12

YW 5.0833 5.3506 12

24-07-2011 5.9000 4.9735 60

CP 5.8333 3.7132 12

DP 5.2500 5.4793 12

ON 4.8333 3.6886 12

WB 6.6667 4.7737 12

YW 6.9167 6.9995 12

25-07-2011 7.1667 5.8778 60

CP 7.1667 5.0782 12

DP 6.5833 6.9079 12

ON 5.8333 4.8586 12

WB 8.0833 5.4516 12

YW 8.1667 7.3588 12

26-07-2011 8.2333 6.9144 60

CP 8.1667 6.5343 12

DP 8.0833 8.5754 12

ON 6.2500 5.2592 12

WB 9.5000 6.2158 12

YW 9.1667 8.1779 12

27-07-2011 9.3333 7.8280 60

CP 9.0000 7.0453 12

43

DP 9.5833 9.6621 12

ON 6.8333 5.9212 12

WB 10.6667 6.9326 12

YW 10.5833 9.5865 12

28-07-2011 13.4500 10.1103 60

CP 13.3333 10.0393 12

DP 15.2500 11.6082 12

ON 8.4167 5.9001 12

WB 15.8333 10.2055 12

YW 14.4167 11.6343 12

29-07-2011 17.4333 14.4085 60

CP 16.5000 12.6095 12

DP 22.5000 18.7010 12

ON 7.7500 5.9563 12

WB 20.5000 13.4401 12

YW 19.9167 15.5064 12

30-07-2011 21.6167 20.2167 60

CP 20.1667 16.7865 12

DP 27.7500 23.5222 12

ON 7.4167 6.5845 12

WB 25.8333 22.0406 12

YW 26.9167 22.6854 12

31-07-2011 25.1500 25.5667 60

CP 24.5000 22.1380 12

DP 31.1667 28.8974 12

ON 7.0833 6.3455 12

WB 29.5000 28.4205 12

YW 33.5000 28.9843 12

8/1/2011 29.5000 31.0541 60

CP 26.5833 25.4789 12

DP 37.3333 36.6143 12

ON 15.0000 24.7533 12

WB 30.8333 30.2830 12

YW 37.7500 35.6527 12

8/2/2011 31.9000 31.9293 60

CP 30.2500 26.1434 12

DP 42.3333 39.6263 12

ON 10.6667 8.5102 12

WB 33.6667 32.5697 12

YW 42.5833 36.6022 12

8/3/2011 36.4000 34.1369 60

CP 34.2500 28.2332 12

44

DP 46.6667 41.7249 12

ON 15.9167 10.6469 12

WB 37.6667 35.2067 12

YW 47.5000 40.5653 12

8/4/2011 42.5000 36.3572 60

CP 41.6667 30.4581 12

DP 53.0000 43.6328 12

ON 21.9167 13.6346 12

WB 41.8333 37.9876 12

YW 54.0833 43.5816 12

8/5/2011 35.4333 32.3211 60

CP 34.0000 25.6267 12

DP 44.8333 39.6641 12

ON 16.9167 12.0488 12

WB 34.9167 32.5505 12

YW 46.5000 39.5210 12

8/6/2011 29.1667 30.4153 60

CP 26.5000 24.5672 12

DP 35.5833 36.7855 12

ON 13.2500 11.2260 12

WB 30.5000 29.7581 12

YW 40.0000 39.1733 12

8/7/2011 19.7333 23.5040 60

CP 19.5000 21.6900 12

DP 26.9167 29.3674 12

ON 6.6667 6.3580 12

WB 18.5833 20.9044 12

YW 27.0000 29.1735 12

8/8/2011 11.0000 16.1182 60

CP 13.6667 18.0722 12

DP 17.5000 22.9367 12

ON 2.4167 3.6546 12

WB 8.2500 9.5644 12

YW 13.1667 16.9804 12

8/9/2011 1.9000 4.4786 60

CP 4.0000 7.6277 12

DP 3.7500 4.5352 12

ON 0.2500 0.8660 12

WB 1.1667 3.4597 12

YW 0.3333 1.1547 12

Grand Total 17.7625 24.3873 1200 Note: a) DP: De Panne, Belgium, b) WB: Westende, Belgium, c) YW: Ynyslas, Wales, United Kingdom

and d) CP: Comporta, Portugal

45

Figures

46

Figure1. Aphids vs. time population growth curve. Each curve represents the aphid-plant

combination per population locality.

Comporta, Portugal

De Panne, Belgium

Westende, Belgium

Ynyslas, Wales, United Kingdom

47

Figure 2. Geographical areas demonstrating seed pool collection points:

a) De Panne, Belgium, b) Westende, Belgium, c) Ynyslas, Wales, United Kingdom and d)

Comporta, Portugal

48

Figure 3. Geographical areas demonstrating seed pool collection points Detailed view of

the two Belgium localities, Westende and De Panne.

49

Figure 4. Geographical area demonstrating seed pool collection point:

Detailed view of Ynyslas, Wales, United Kingdom.

50

Figure 5. Geographical area demonstrating seed pool collection point:

Detailed view of Comporta, Portugal.

51

Appendix

52

Appendix 1. Example of data collection sheet

53

Appendix 2. Ghent University acceptance letter

54

Appendix 3. Ammophila arenaria host plants and aphids (Schizaphis graminum)

Note: that the aphid in the picture is Schizaphis graminum and not Schizaphis rufula,

nonetheless they look very similar and have the same biology and life cycle. Little or no

photographs can be found of Schizaphis rufula. Photograph demonstrates use of host

plants for parthenogenesis.

2) Schizaphis graminum, greenbug

3) Ammophila arenaria host-plants

3

55

Appendix 4. Experimental seedlings planted on the pots

56

Appendix 5. Ammophila arenaria grass in-situ: Het Zwin Nature Reserve, Knokke-Heist,

Belgium

57

Appendix 6. Central mobile dune system in Het Zwin Nature Reserve, Knokke-Heist,

Belgium

58

Appendix 7. Dune ecosystem access restriction, De Panne, Belgium

UNIVERSIDAD METROPOLITANA SCHOOL OF ENVIRONMENTAL AFFAIRS ...€¦ · UNIVERSIDAD METROPOLITANA. SCHOOL OF ENVIRONMENTAL AFFAIRS. SAN JUAN, ... Foundation and its coordinator Lisa

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